Sehgal index: A new index and its comparison with other complete blood count-based indices for screening of beta thalassemia trait in a tertiary care hospital

Abstract

Introduction: Beta thalassemia trait (BTT) must be differentiated from iron deficiency anemia to avoid unnecessary iron therapy and for the prevention of thalassemia major by genetic counseling. In a tertiary care hospital, it is vital that the screening tool is not only sensitive but also specific so as to be cost effective and save time. Aim: The aim of this study was to evaluate the new Sehgal index and compare it to existing complete blood count-based indices for the best combination of sensitivity and specificity to predict BTT. Materials and Methods: Study was done in 2 phases - Phase 1: A retrospective analysis of 1022 consecutive high-performance liquid chromatography (HPLC) cases from July 2008 to June 2011. Phase 2: A prospective analysis of 973 consecutive HPLC cases from July 1, 2011 to June 10, 2013 was done to confirm the results of Phase 1 and the applicability of the new Sehgal index. Results: Prevalence of BTT was 28.8% (294/1022) and 25.39% (247/973) in Phase 1 and Phase 2, respectively. Receiver operating characteristic-area under the curve and Youden index was highest for new Sehgal index, followed by Mentzers index <14. The prospective study shows results similar to those in Phase 1 confirming the superiority of the above two indices. Conclusion: Sehgal index and Mentzers index <14 showed the best combination of sensitivity and specificity in predicting BTT. The best indices or combination can be used as a "validated flag rule" in the analyzer middleware program in a hospital for identifying suspected cases of BTT.

Keywords

• Beta thalassemia trait
• complete blood count
• iron deficiency anemia
• mentzers index
• Sehgal index